Stuck in Pending Reboot Cycle

Hello again,

Microsoft released a bunch of security updates on March 2, 2021 (KB5000871) addressing a number of Exchange server vulnerabilities. Details here. But that's not the point of this post.

Exchange admins, myself included, started rolling out the update. However in one instance a server was stuck in a "pending reboot" state:

The information for pendingreboot is stored in the Registry. Not wanting to rediscover the wheel, searched for an easy way out: a script which looks for entries that control pending reboots.

Came across Adam Bertram's article. He not only has a good list of Registry entries to check, but provided a PowerShell script also to make it easy.

Using his script I quickly found that the RebootPendinig Registry key was present. The script in its original form only shows whether it is pending reboot or not, but it doesn't show which key or value it is. I altered the script to show this detail also:

Checking in Registry Editor confirmed it:

Please note that it is an empty key. Its sheer presence will trigger the pending reboot condition.

For more on this key see this Microsoft Scripting Guy article.

Having rebooted the computer, it was safe to delete the key. But...:

The fix:

1. Took ownership of the key. The original owner is System.
2. Added myself with Full Access permissions.
3. Delete the key.

Once the key was deleted, the patch installed just fine.

Until next time.